Sporadic Apolipoprotein A‐II Amyloidosis With Familial Renal Failure: A Mutation‐Negative Case and Comprehensive Literature Review

We report a 32-year-old man who presented with proteinuria and a family history of renal failure. A renal biopsy revealed amyloid deposit in the glomeruli, renal interstitium, and arterioles. An abdominal fat aspirate was also positive for amyloid deposition. Following comprehensive evaluation, both acquired monoclonal immunoglobulin light chain amyloidosis (AL-type) and reactive amyloid A amyloidosis (AA-type) were excluded. Mass spectrometry analysis of the renal amyloid material indicated the presence of apolipoprotein A-II (ApoAII) amyloidosis. However, genetic sequencing did not identify any mutation in the coding sequence of ApoA-II. We discuss the rarity, aetiology, diagnosis, and management of apolipoprotein A-II amyloidosis.